Got rid of whatraw().
Doc-string-ified the lead comments. Added auto call of test() when run as script.
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Lib/sndhdr.py
107
Lib/sndhdr.py
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@ -1,85 +1,45 @@
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# This module contains several routines that help recognizing sound
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# files.
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#
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# Function whathdr() recognizes various types of sound file headers.
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# It understands almost all headers that SOX can decode.
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#
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# The return tuple contains the following items, in this order:
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# - file type (as SOX understands it)
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# - sampling rate (0 if unknown or hard to decode)
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# - number of channels (0 if unknown or hard to decode)
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# - number of frames in the file (-1 if unknown or hard to decode)
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# - number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW
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#
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# If the file doesn't have a recognizable type, it returns None.
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# If the file can't be opened, IOError is raised.
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#
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# To compute the total time, divide the number of frames by the
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# sampling rate (a frame contains a sample for each channel).
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#
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# Function whatraw() calls the "whatsound" program and interprets its
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# output. You'll have to guess the sampling rate by listening though!
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#
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# Function what() calls whathdr() and if it doesn't recognize the file
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# then calls whatraw().
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#
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# Finally, the function test() is a simple main program that calls
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# what() for all files mentioned on the argument list. For directory
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# arguments it calls what() for all files in that directory. Default
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# argument is "." (testing all files in the current directory). The
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# option -r tells it to recurse down directories found inside
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# explicitly given directories.
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#
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"""Routines to help recognizing sound files.
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Function whathdr() recognizes various types of sound file headers.
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It understands almost all headers that SOX can decode.
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The return tuple contains the following items, in this order:
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- file type (as SOX understands it)
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- sampling rate (0 if unknown or hard to decode)
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- number of channels (0 if unknown or hard to decode)
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- number of frames in the file (-1 if unknown or hard to decode)
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- number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW
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If the file doesn't have a recognizable type, it returns None.
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If the file can't be opened, IOError is raised.
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To compute the total time, divide the number of frames by the
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sampling rate (a frame contains a sample for each channel).
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Function what() calls whathdr(). (It used to also use some
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heuristics for raw data, but this doesn't work very well.)
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Finally, the function test() is a simple main program that calls
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what() for all files mentioned on the argument list. For directory
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arguments it calls what() for all files in that directory. Default
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argument is "." (testing all files in the current directory). The
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option -r tells it to recurse down directories found inside
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explicitly given directories.
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"""
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# The file structure is top-down except that the test program and its
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# subroutine come last.
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#------------------------------------------------------#
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# Guess the type of any sound file, raw or with header #
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#------------------------------------------------------#
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#--------------------------------#
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# Guess the type of a sound file #
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#--------------------------------#
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def what(filename):
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res = whathdr(filename)
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if not res:
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res = whatraw(filename)
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return res
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#-----------------------------#
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# Guess the type of raw sound #
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#-----------------------------#
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def whatraw(filename):
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# Assume it's always 1 channel, byte-sized samples
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# Don't assume anything about the rate
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import os
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from stat import ST_SIZE
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# XXX "whatsound" should be part of the distribution somehow...
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cmd = 'whatsound ' + filename + ' 2>/dev/null'
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cmd = 'PATH=$PATH:/ufs/guido/bin/sgi\n' + cmd
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pipe = os.popen(cmd, 'r')
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data = pipe.read()
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sts = pipe.close()
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if sts:
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return None
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if data[:13] == '-t raw -b -s ':
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type = 'sb'
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sample_size = 8
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elif data[:13] == '-t raw -b -u ':
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type = 'ub'
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sample_size = 8
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elif data[:13] == '-t raw -b -U ':
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type = 'ul'
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sample_size = 'U'
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else:
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return None
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try:
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frame_count = os.stat(filename)[ST_SIZE]
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except IOError:
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frame_count = -1
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return type, 0, 1, frame_count, sample_size
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#-------------------------#
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# Recognize sound headers #
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#-------------------------#
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@ -268,3 +228,6 @@ def testall(list, recursive, toplevel):
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print what(filename)
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except IOError:
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print '*** not found ***'
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if __name__ == '__main__':
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test()
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